GLAUCOMA AND HEARING LOSS

 

DR FARHAT JAHAN

P.G. SCHOLAR

Department of Amraz Ain, Uzn, Anf, Halaq wa Asnan,

State Unani Medical College and Hospital

Prayagraj, India

A systematic literature review was performed by Meliante and colleagues to look into the association of glaucoma with hearing loss. Their review analyzed 30 studies across various databases.

WHAT IS SENSORINEURAL HEARING LOSS?:

• Sensorineural hearing loss (SNHL) refers to hearing impairment secondary to cochlear abnormalities and/or damage to the cochlear nerve or the central auditory pathways.
• The most common form of SNHL is age-related hearing loss, characterized by a gradual and symmetrical decrease in hearing sensitivity, particularly at higher frequencies.
• It affects over 60% of individuals aged sixty-five and above.
• SNHL is a complex condition influenced by various factors, including gender, ethnicity, noise exposure, ototoxic medications, lifestyle choices, comorbidities, and genetic predisposition.
• SNHL is associated with a higher prevalence of neurodegenerative or neurological diseases like Alzheimer’s, cognitive impairment, or general dementia, through both common and causal mechanisms.
• These factors are also associated with the development of glaucoma.

SNHL AND PSEUDOEXFOLIATIVE GLAUCOMA:

• Several studies have reported increased pure tone audiometry (PTA) thresholds at speech frequencies (0.25, 0.5, 1 and 2 kHz) in patients with pseudoexfoliative syndrome (XFS)
• Singham et al. found a higher prevalence of hearing loss in individuals with XFS and significantly higher hearing thresholds at 0.5 and 1 kHz compared to controls (p < 0.05).
• Temporale et al. (2016), detected abnormal PTA at 2 kHz in 87% of XFS patients compared to 64.3% of controls (p = 0.008), and Lee et al. (2017) found XFS patients to have moderate to severe SNHL in 64% of cases (vs. 40.3% in controls) with an average hearing threshold of 47.93 dB, corresponding to the moderate hearing loss category according to the ISO 1964 and significantly decreased PTA at 1 and 2 kHz.
• Others have found an association between SNHL and pseudoexfoliation at all frequencies. SNHL at speech frequencies (mean value of 0.5, 1 and 2 kHz) in 69% of XFS patients vs. 52% of controls (p = 0.03) with a significantly higher mean threshold value (33.6 ± 18.5 dB vs. 28.4 ± 15.0 dB, p = 0.01).
• Papadopoulos et al. found a higher prevalence of PTA hearing loss in XFS patients at both low frequencies (0.25 & 0.5 Hz—57% vs. 41%, p = 0.07), medium frequencies (1 & 2 kHz—81% vs. 59%, p = 0.007) and high frequencies (4 & 8 kHz—98% vs. 86%, p = 0.007), with more severe hearing loss noted at 4 and 8 Hz.
• However, Muhafiz and also Tryggvason did not find any association between SNHL and pseudoexfoliation.
• The mechanism of association between SNHL and pseudoexfoliation can be explained by the dysfunction of hearing mechanoreceptors due to the deposition of fibrillar material in either or both the tectorial and basilar membranes, impairing the transmission of vibrating energy to the sensory hair cells, hence the conversion of the vibration energy to bioelectric energy. An alternative mechanism is vascular compromise due to the deposition of pseudo-exfoliative fibrils in the vessel walls.

SNHL AND PRIMARY OPEN ANGLE GLAUCOMA (POAG):

• In the study by Meliante and colleagues, 36% of POAG participants experienced difficulty differentiating low-frequency sounds. These findings indicate that some individuals with POAG may have an increased central nervous system vulnerability to damage, leading to auditory and visual processing dysfunction.
• A study by Kim et al. on the Korean population showed that aging and increased triglyceride levels were independent risk factors for the simultaneous occurrence of POAG and hearing impairment.

SNHL AND NORMAL TENSION GLAUCOMA (NTG):

• Regarding the potential correlation between NTG and progressive SNHL, some authors have focused on the role of autoantibodies against antigens in the inner ear.
• Patients with NTG had significantly higher concentrations of IgG APSA compared to controls (p<0.05), and elevated APSA concentrations showed significantly higher concentrations in NTG with progressive SNHL compared to NTG patients with normal hearing (p<0.01). Significantly higher concentrations of IgG APSA in NTG with progressive SNHL compared to normal hearing and controls were also found by Bachor et al., who additionally found the concentrations of IgM APSA were significantly elevated in all subgroups of NTG patients, as well as in NTG patients with normoacusis, compared to controls.

CONCLUSION:

These studies show a significant association of glaucoma with SNHL. Therefore, all patients having SNHL should be investigated for glaucoma and vice versa.

REFERENCE:

Meliante LA, Piccotti G, Tanga L, Giammaria S, Manni G, Coco G. Glaucoma, Pseudoexfoliation and Hearing Loss: A Systematic Literature Review. J Clin Med. 2024;13:1379.